Tuesday, November 1, 2011

Frank Van Alstine is noted for his no-frills superb sounding, hand-built amplifiers and preamps, as well as his long-running upgrade mods to classic Dynaco gear. But he also realizes that the hi-fi world is firmly rooted in the digital. Hence, his series of D/A converters, including the Vision DAC Hybrid reviewed here, follows the pattern of his well-regarded analog components.

The Vision Hybrid DAC, priced at $1,995, that I tested here is a hybrid tube/solid-state analog-to-digital converter that offers a silky smooth approach to DACs. Plug in a digital signal via TOSlink or SPDIF — up to 24/bit 192 kHz — and connect the RCA outputs to your preamp and play music.

Features

Compared to other converters that have USB inputs, SD card readers, etc., the AVA Vision Hybrid DAC is kind of old school; it sports an off/on switch, digital selector on the front panel, two SPDIF and two Toslink inputs, and one set of RCA output jacks on the back. That’s it — not even a headphone amp. Its AVA family resemblance is instantly recognizable — with its simple, black metal chassis and vented top panel. Although my review unit came with a fixed two-prong power cord, AVA now offers three-prong, detachable IEC cords as standard. The AVA DAC also is equipped with three accessory outlets, circa 1960s style, for two-prong AC products, such as a preamp, etc. I used the handy feature for plugging in a LCD for BD player reference.

All AVA products are sold direct from the factory to the customer. I have found that AVA can turn out an ordered product in just a few weeks, depending on demand.

Inside, the DAC is a clean, hand-assembled assortment of parts that ultimately allows this Vision Hybrid DAC to convert 1s and 0s into some seriously real-sounding music. The heart of the design is a Wolfson 8742 DAC chip set — for synchronous digital conversion duties — and its premium analog components, including a pair of Russian 6CG7 tubes operated in a hi-current, medium-mu circuit in the analog output. The DAC’s analog filter also runs through the tube stage.

Although it may look pedestrian in its appearance, the Audio-by Van Alstine Vision Hybrid DAC is a terrific sounding, no-frills D/A converter. Its performance ranks up there with those costing considerably more money.

The Vision Hybrid DAC has eleven regulated power supplies, including separate regulated power supplies for the tube heater circuits, the digital circuits and an independent high-voltage, high-current, analog regulated power supply for each plate of each tube and each power MOSFET used in AVA’s patented trans-impedance amplifier sections. The DAC handles any sample rate up to 192 khz, though you have to remove the cover to access the highest sampling frequency. The factory-set, jumper setting enables up to 96 kHz.

AVA also offers the solid state, one RCA coax input Vision DAC and the four-input Vision EC DAC with an XLR balanced line output option. Unfortunately, the Vision DAC Hybrid does not get the XLR output at this time. Frank Van Alstine said that the Hybrid may get the balanced option in the future.

All Vision DACs can be optioned for extra gain, via additional components in the analog stage. My unit did not have the gain option, but I did notice that its output was several dB down versus the other DACs I was using. My preamp could make up for the decreased gain, but those with low-gain or passive preamps may want to opt for the extra output.

The setup

I connected the Vision Hybrid DAC to my primary audiophile system, as well as my home recording rig, using an Apple Macbook Pro as the source. Music ranged from well-recorded CDs, home-recorded jazz and acoustic guitar music, HD Tracks 24 bit downloads, DVD-Audio discs and hi-res Blu-rays.For comparison, I had on hand my Benchmark DAC1 Pre, Lavry DA10, and the internal converters of the Oppo BDP-95 and Esoteric DV-50 universal players. I used an AVA EC hybrid preamp for headphone listening, via a set of AKG K701 headphones, and a Coda preamp for feeding the line signal to the amp for speaker listening. The big monitoring system included a Pass Labs X-350.5 amplifier, and Legacy Focus 20/20 speakers wired with Alpha-Core solid silver cables. All IEC cord components were plugged into an Essential Sound Products Essence power strip using Essence power cords.Since the Vision Hybrid DAC uses vacuum tubes, I turned on the unit and let it burn in for a few days. Listening to the noise floor via the headphones and the AVA EC preamp's headphone amp, the Russian Electro-Harmonix tubes were extremely quiet.For comparison, I used the Oppo BDP-95 as the source (up to 192 kHz/ 24-bit from the digital output), feeding the Vision DAC and one of the other test DACs, which were connected to the AVA EC or Legacy/Coda preamp.The AVA DAC output was several decibels lower in output level, so I adjusted the variable volume control of the Lavry and Benchmark, using test tones and a level meter for reference to match their output levels.

The auditionFirst up, I chose the “Carnival” track from the Natalie Merchant — Tigerlily DVD-A, a 24-bit transfer of an original 1990s analog recording. The opening minute has a warm, yet open, detailed intro of bass, electric guitar and drums. I always listen to the drum cymbals with a tested product to see how much of the room ambiance and the width of the transients get translated through the electronics and to the speakers. Most good DACs decode that extra degree of detail and realism of the recorded track without it sounding unnatural; lesser converters can blur it slightly.The Vision Hybrid DAC’s ability to relay those drum cymbal transients and the separation of the other instruments in the mix was as good as most other converters I have heard in the $2,000 to $3,000 price range. And thanks to the tube/MOSFET circuit in the analog path, the AVA’s sound was ultra-smooth, not a hint of harshness.

But the Vision Hybrid DAC presented the 2L music, especially the cut Andreas Andre, with incredible precision and snap-to-attention transients; it was never harsh or overblown. In my opinion, this converter can hang with the best of them.

Although it is tough to hear major differences between quality converters when the levels are precisely matched, the Benchmark’s sound was smooth, but slightly more analytical and tight; the Lavry a little less smooth. Compared to the first-generation Esoteric DV-50s up-sampling PCM converters, the Vision DAC was smoother by far. The Oppo BDP-95 exhibited a clean smoothness to its aural palette as well, but I liked the width and depth of the AVA’s stereo playback just a touch more.Noting this soothing quality of the Vision DAC, I popped in the Fleetwood Mac — Rumours DVD-A, which has considerable high-frequency energy and can sound a little course through lesser converters. Again, the Vision Hybrid DAC showed its stuff, with a highly listenable, upper-end texture that befits such a classic recording. The track "Oh Daddy" was particularly noteworthy.Next up, was some high-res world music from the 2L music Blu-ray label. The drums and vocal Jieant — Mirta album is an expansive drum and vocal performance with tremendous detail, width and dynamic range at 24-bit 192 kHz. With the right system, it can sound like it is literally in the room. I have found that with marginal, mostly low-cost blu-ray players, the stereo image width shrinks a bit and is not quite as full as with really good converters.But the Vision Hybrid DAC presented the 2L music, especially the cut "Andreas Andre," with incredible precision and snap-to-attention transients; it was never harsh or overblown. In my opinion, this converter can hang with the best of them.The observed sonic characteristics were confirmed via headphone listening as well. Through the AVA EC preamp, I could hear the width and depth. Plus the lack of harshness in the dynamic parts enabled me to really dial-in on the low level detail via the AKG K701s.On playback of my home brew acoustic guitar music, recorded via a TASCAM HDP2 Flash recorder, a Benchmark ADC1 A/D front end, True Systems P2 stereo mic preamp and a pair of Shure KSM141 microphones, the high-res playback tracks were terrific through the AVA Vision DAC Hybrid. The result was a spacious, open, 24-bit sound with plenty of plucked string transient detail and subtle room reverb from my Martin J-40 rosewood, sitka spruce top guitar. I was really impressed with the Vision DAC's lack of noise. Tube grading and a well-designed circuit that includes a tube stage analog filter really works.

Vision DAC Tube Section

I have only a few gripes about the Vision Hybrid DAC. I wish it had a headphone amp. AVA offers the Vision DAC Preamp, a combo of the solid-state Insight preamp and Vision DAC, but it does not have the upgraded parts and tube stage of the solo Vision Hybrid DAC. And how about a front-panel switch to select the 192 kHz mode — instead of having to remove the Torx screws, pull the cover and move a jumper. Lastly, the XLR output option is not available on the Vision DAC Hybrid, only the Vision DAC EC.Some audiophiles may wish for a USB connection, but Frank Van Alstine says he does not want to get into the software support side of the biz by having to create audio drivers for his products. He said that audio accessory companies manufacture USB-to-TOSlink adapters that can allow for USB connection to the Vision Hybrid DAC, or just use it with a computer that has Toslink or SPDIF connections on a sound card.When it comes to pricing some may feel that $2,000 is a lot of money for a basic line DAC. However, the two-grand price tag does not bother me. It is, afterall, made in USA, and the build is exemplary.The verdictAlthough it may look pedestrian in its appearance, the Audio-by Van Alstine Vision Hybrid DAC is a terrific sounding, no-frills D/A converter. Its performance ranks up there with those costing considerably more money. The detailed, yet ultra-smooth, sonic delivery with CD, high-bit rate DVD-As, web audio downloads and Blu-rays make it a contender for those want a quality line-level DAC. I see an Everything Audio NetworkStellar Sound Award for this Vision DAC.